Infrared reflectance and transmission spectra in II-VI alloys and superlattices

Devki N. Talwar, Tzuen Rong Yang, Zhe Chuan Feng, P. Becla

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Abstract

Room temperature measurements of the far-infrared (FIR) reflectance spectra are reported for the polar optical phonons in a series of bulk Cd xZn1-xTe (0 ≤ x ≤ 1) and CdSexTe 1-x (0 < x ≤ 0.35) crystals grown by Bridgman technique. The composition-dependent spectra exhibited many fundamental aspects of lattice vibrations, while the results of long-wavelength optical modes for the end member binary compounds displayed phonon values in good agreement with the existing inelastic neutron scattering and/or Raman spectroscopy data. Using a standard methodology of multilayer optics with effective-medium dielectric tensors, we simulated the FIR transmission and reflectivity spectra at oblique incidence (Berreman's effect) in many II-VI free-standing thin films, epilayers and superlattices. Berreman's approach provided us with a strong basis for analyzing the infrared experimental data and offered an effective means of estimating the zone-center transverse and longitudinal optical (ωTO, ωLO) phonon frequencies in polar-semiconductor thin films and heterostructure materials of increasing technological importance.

Original languageEnglish
Article number174203
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume84
Issue number17
DOIs
Publication statusPublished - 2011 Nov 8

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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